The number of different radios in a mobile communication device is steadily increasing to facilitate more flexible connectivity and a broader range of services. Cellular access alone is no longer sufficient, but new wireless technologies are integrated into communication devices now and especially in the future to enable novel connectivity solutions. Integration of multiple radios into a single terminal, however, introduces a serious integration challenge that is becoming more pronounced as the number of radios increases. One element of the integration challenge is the appropriate handling of simultaneous operation of radios. It is quite evident that users are willing to use different radios at the same time, like using a headset employing wireless Bluetooth® technology during a GSM phone call, and using a wireless local area network (WLAN) connection for Internet browsing, for example.
If there are two or more operational radio connections from one communication device, the connections may very well interfere with one another. Even if the connections are not operating on the same frequency band, they may still interfere with each other due to the non-idealities in the components' of the communication device. The components may introduce spectral leakage, and the selectivity of receivers may not be ideal, meaning that they may also receive signal components belonging to a signal other than the desired one.
Mobile telecommunication systems have adopted a hybrid automatic repeat request (HARQ) scheme for packet radio services in order to enable reliable and fast transfer of data packets. Mobile telecommunication systems employing the HARQ scheme include Wimax, high-speed packet access (HSPA) of Universal Mobile telecommunication System (UMTS) based on wideband code division multiple access (W-CDMA), and a Fast Low-latency Access with Seamless Handoff Orthogonal Frequency Division Multiple Access (FLASH-OFDM). Many of upcoming wireless telecommunication systems will be utilizing HARQ, too.
In a multiradio communication device, the level of the interference caused by one connection to another may be significantly high due to the close proximity of transmitters and receivers. Accordingly, a problem with the conventional HARQ is that a data packet received under a strong interference will be detected and decoded. Probably, the decoding of the data packet was not successful and, thus, the decoded data contains errors. The information obtained from the data packet will then be stored and combined later with retransmissions of the same data packet in order to decode the payload information correctly. Accordingly, the data packet received under the strong interference and containing a significant amount of errors may hinder data detection in the combining stage considerably.